From owner-freebsd-hackers@FreeBSD.ORG Mon Nov 12 23:09:54 2012 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id E07A8B7A; Mon, 12 Nov 2012 23:09:54 +0000 (UTC) (envelope-from alc@rice.edu) Received: from mh3.mail.rice.edu (mh3.mail.rice.edu [128.42.199.10]) by mx1.freebsd.org (Postfix) with ESMTP id AA65A8FC0C; Mon, 12 Nov 2012 23:09:54 +0000 (UTC) Received: from mh3.mail.rice.edu (localhost.localdomain [127.0.0.1]) by mh3.mail.rice.edu (Postfix) with ESMTP id A1E864018D; Mon, 12 Nov 2012 17:09:53 -0600 (CST) Received: from mh3.mail.rice.edu (localhost.localdomain [127.0.0.1]) by mh3.mail.rice.edu (Postfix) with ESMTP id A0DBE4018C; Mon, 12 Nov 2012 17:09:53 -0600 (CST) X-Virus-Scanned: by amavis-2.7.0 at mh3.mail.rice.edu, auth channel Received: from mh3.mail.rice.edu ([127.0.0.1]) by mh3.mail.rice.edu (mh3.mail.rice.edu [127.0.0.1]) (amavis, port 10026) with ESMTP id XAR2eXVjcQkA; Mon, 12 Nov 2012 17:09:53 -0600 (CST) Received: from [10.212.194.246] (unknown [10.212.194.246]) (using TLSv1 with cipher RC4-MD5 (128/128 bits)) (No client certificate requested) (Authenticated sender: alc) by mh3.mail.rice.edu (Postfix) with ESMTPSA id 84D2540186; Mon, 12 Nov 2012 17:09:53 -0600 (CST) Message-ID: <50A181C9.7030209@rice.edu> Date: Mon, 12 Nov 2012 17:10:01 -0600 From: Alan Cox User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:12.0) Gecko/20120428 Thunderbird/12.0.1 MIME-Version: 1.0 To: Konstantin Belousov Subject: Re: Memory reserves or lack thereof References: <20121112133638.GZ73505@kib.kiev.ua> <1352755682.93266.YahooMailClassic@web181701.mail.ne1.yahoo.com> <20121112214808.GH73505@kib.kiev.ua> In-Reply-To: <20121112214808.GH73505@kib.kiev.ua> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: alc@freebsd.org, pho@freebsd.org, Sushanth Rai , StevenSears , "freebsd-hackers@freebsd.org" X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 12 Nov 2012 23:09:55 -0000 On 11/12/2012 3:48 PM, Konstantin Belousov wrote: > On Mon, Nov 12, 2012 at 01:28:02PM -0800, Sushanth Rai wrote: >> This patch still doesn't address the issue of M_NOWAIT calls driving >> the memory the all the way down to 2 pages, right ? It would be nice to >> have M_NOWAIT just do non-sleep version of M_WAITOK and M_USE_RESERVE >> flag to dig deep. > This is out of scope of the change. But it is required for any further > adjustements. I would suggest a somewhat different response: The patch does make M_NOWAIT into a "non-sleep version of M_WAITOK" and does reintroduce M_USE_RESERVE as a way to specify "dig deep". Currently, both M_NOWAIT and M_WAITOK can drive the cache/free memory down to two pages. The effect of the patch is to stop M_NOWAIT at two pages rather than allowing it to continue to zero pages. When you say, "This is out of scope ...", I believe that you are referring to changing two pages into something larger. I agree that this is out of scope for the current change. Alan